Preamp build suggestions

[tubeampking]

Looking to build my own all tube, stereo phono preamp. Preferably 12AX7 or 12AU7 based. Anyone have any suggestions for resources ? Even a kit would be ok, something intermediate ...thanks.

 

[enzoazul]

I've heard good things about the Bottlehead kits.. though I haven't built one myself.

http://bottlehead.com/phono-preamplifier-kits/

Would certainly be cool to have an AudioKarma group buy scenario for some kind of tube phono preamp design. More specifically, a kit/design that was all hand wired point to point instead of printed circuit boards.

 

[JohnW]

You can buy a bare Dynaco PC-6 board for a 12AX7 phono preamp from eBay or a number of other sites.
The phono preamp from the Dynaco Pas2/3 series sounds good, and is well documented on-line. You'd have to source the parts and build up your own power supply, though.
I like the phono section from the Eico HF-85 which is another fairly simple 2-tube 12AX7 circuit.

 

[gadget73]

If you're up for a full-on homebrew, clone the Pilot SP-210 circuit. uses four 12AX7's to give a line stage with tone controls and a phono stage. It won't drive a low impedance amp, but should do just ducky into a tube amp. If you've got a console amp hanging around that is no longer powering a tuner, I bet you've even got all the power supply you need. The SP-210 originally powered off the amplifier.

 

[jaymanaa]

If you want easy and good sound, the circuit in the back of the old RCA tube manuals is a good one. There is a circuit also, for tone controls that mates to it if you want. If you want harder than hell, but sounds incredible, the 6DJ8 is the best I've heard by far.

 

[Trio]

Hmmm. Gives me an idea for those DJ8's i have had kicking around. Was that circuit in the 1967 edition or was it the one earlier?

 

[battradio]

http://www.classicvalve.ca/tubepcb.html

Look here there is a lot to choose from

 

[whoaru99]

I have two tube kit builds, a Transcendent Sound Grounded Grid preamp, and a recently-acquired Bottlehead Crack headphone amp that also works as a preamp. The Grounded Grid uses three 12AU7s, the Bottlehead uses a 12AU7 or variant, and a 6080 or variant.

The GG sounds quite good to me, although I don't have a lot of experience with various tube pres. General consensus around forums seems to be it sounds very good, albeit not particularly "tubey".

Last night was the first night I tried the Bottlehead as a preamp. It seemed to work pretty good albeit I don't really need that much gain since the source is strong coming out of a DAC. Also, since it has only one input it's not directly conducive to one having multiple sources. The GG has a 3-input selector.

 

[tubeampking]

http://www.classicvalve.ca/tubepcb.html

Look here there is a lot to choose from

Thanks for that. The Budgie looks like what I'm aiming at. The Bottleheads are way too pricey for me. Getting a board and schematic is really what I'd prefer. I have a bunch of caps, resistors, hookup wire etc.
Another approach was to maybe copy the preamp section of my Grommes LJ-4, build it as two independent signal paths, and add a power supply. Thinking about a bridge rectifier for the tighter bass, but then it wouldn't bee all tube. Thoughts? :scratch2: + =

 

[PR Audio]

There is a vendor on EBay, I believe the store name is 8Audio. They have PCB's for different tube pre and amp designs: Marantz, CJ, and many other well known and proven design. They also sell the boards with components assembled, and you can add phono stage, power supply, etc. I have not heard an assembled DIY pre or amp using their boards, but I've read their boards are an exact match of the original circuitry schematics.


Sent from my iPhone using Tapatalk

 

[jaymanaa]

Once I started using SS diodes, I haven't really looked back. The only reason I would pick tube over SS for rectification duty would be aesthetics. You can get you a couple 1N4007s for around 50 cents each and go to town.

 

[kward]

Another approach was to maybe copy the preamp section of my Grommes LJ-4, build it as two independent signal paths, and add a power supply. Thinking about a bridge rectifier for the tighter bass, but then it wouldn't bee all tube. Thoughts? :scratch2: + =

There shouldn't be any difference in bass performance with solid state rectifiers vs tube rectifiers. Just need to design the supply to deliver the B+ or rail voltages you desire. So I say use which ever is easier. I tend to prefer solid state bridge rectification these days just cuz it's cheaper and more efficient (less winds on the power transformer, runs a heck of a lot cooler) and takes less space and sounds just as good. I typically use UF4007 diodes, or equivalent soft recovery types, but at the minuscule (relatively speaking) current that a phono preamp would draw, I think even 1N4007 types would be fine.